1. Field of the Invention
The field of the present invention concerns machines for resurfacing disc brake rotors, and brake drums, and more specifically relates to a detachable damper for minimizing harmonic vibrations of the rotor or drum when it is subjected to a machining operation to renew its braking surfaces.
2. Description of Prior Art
In some resurfacing machines for disc brake rotors, both sides of the disc are simultaneously ground to insure absolute parallelism of the braking surfaces. In other machines, each side of the rotor is separately resurfaced. During either type of resurfacing operation, it is conventional practice to have mounted on the rotor disc an auxiliary damping device which will surpress or prevent harmonic vibrations in the discs, which vibrations would otherwise cause some degree of chatter and impair the smoothness of the surface created by the machining operation.
A disc brake resurfacing machine is disclosed in my U.S. Pat. No. 3,500,589 which issued on Mar. 17, 1970, and is incorporated by reference herein. The vibration damper of the present invention may be mounted on disc brake rotors resurfaced by the machine disclosed in my patent.
In regard to vibration dampers, the U.S. Pat. No. 3,611,830, to Shank which issued on Oct. 12, 1971, includes a spring tensioned loop which engages the peripheral edge of a brake rotor disc and carries lead weights that will alter and damp the resonance response to the disc. The patentee specifically states that iron weights were tried but did not successfully reduce vibration, and accordingly, he has relied upon more expensive lead weights. The Shank device also specifically recognizes and meets the problem of accommodating the simultaneous machining of both radial surfaces of the disc.
Another U.S. Pat. No. 3,345,884, to Kuderko issued on Oct. 10, 1967 also concerns the problem of damping vibrations in a disc brake rotor undergoing an operation to refinish its braking surfaces. In this patented device, a generally U-shaped frame carries permanent magnets which function both as weights and as attachment means for the frame. The frame is fixed to one radial surface while the other radial surface is being refinished, and of course, the device is limited to brake disc rotors of ferrous material.
Other patents of general interest concerning brake dampers are Fosberry, U.S. Pat. No. 2,941,631 and Huck, U.S. Pat. No. 1,846,257, both of which disclose brake drum dampers used to prevent or suppress vibrations under operating conditions by engagement with the axial wall portion of the brake drum. Only the Shank Patent supra, is considered to be applicable to both disc type and drum type brakes in a resurfacing operation.